Functional and physical properties of sorghum-based extruded product supplemented with soy meal flour

Abstract

Effects of soy meal flour (0, 10, and 20%), barrel temperature (135, 150, and 165°C) and feed moisture content (15, 18, and 21%) on functional properties [water absorption index (WAI), water solubility index (WSI) and water holding capacity (WHC)] and physical properties [specific length (SL), diametric expansion (DE), bulk density (BD), and hardness (H)] of sorghum based extruded product were studied using factorial design. Increasing the level of soy meal flour resulted in increase in WAI, WSI, WHC, BD and H from 6.05 to 7.27 g/g, 7.51 to 8.62%, 7.82 to 8.51 g/g, 0.24 to 0.36 g/cm3, and 96.48 to 112.77N, respectively, while DE and SL were decreased from 2.16 to 1.76 and 1.23 to 1.16 cm/g, respectively. A significant higher WSI (8.07 and 8.04%) and DE (2.14 and 2.17), and lower WAI (6.26 and 6.50 g/g), BD (0.24 and 0.26 g/cm3) and H (93.14 and 100.11N) were observed at the lower feed moisture content (15%) and higher barrel temperature (165°C), respectively. Generally, extrudate made from lower level of soy flour at low feed moisture and high barrel temperature had better functional and physical properties.